<html>
    <head>
        <title></title>
    </head>
  <body>
    <div id="main">
        <h1>Hello Extensions</h1>
        <script src="popup.js"></script>
    </div> 
  </body>
  <style>
   html,body{ width:500px; height:100%;}
   #main{min-width: 100%;
	    min-height: 100%;
	    position: absolute;}
  </style>
</html>